International Patent Application Publication No. (WO) 98/24767, European Patent Application Publication No. (EP) 933363, European Patent Application Publication No. (EP) 959071 and International Patent Application Publication No. (WO) 2005/060749 all describe arylpyrazoles having parasiticidal activity for the control of arthropods.
However, the prior art compounds do not always demonstrate good activity or a long duration of action against parasites. Similarly, some of the prior art parasiticidal agents are useful only for a narrow spectrum of parasites. In some cases this may be attributed to the low bioavailability of the compounds in the treated animal and this can also lead to poor activity. It is an aim of the present invention to overcome various disadvantages of, or improve on, the properties of prior art compounds. Thus it is an aim of the invention to provide an arylpyrazole which has the same or improved activity relative to prior art compounds against parasites. It is a further aim of the present invention to provide arylpyrazole compounds with improved bioavailability whilst maintaining or improving their activity. The compounds of the present invention have especially good ability to control a broad spectrum of arthropods as shown by the results of tests demonstrating their potency and efficacy. In particular, the compounds of the present invention are significantly more active against fleas than similar prior art compounds.
It is a further aim to provide compounds with a long duration of action. Surprisingly it has been found that improving the bioavailability of the compounds does not negatively impact their duration of action. The extended duration of action is generally attributed to an extended half life of the compound in vivo in the host mammal.
It is also desirable that the compounds of the present invention should have an improved pharmacokinetic profile, improved safety, improved persistence and improved solubility.